GPT-5.5 Pro
OpenAI · 2026-04-23
GPT-5.5 Pro is OpenAI's higher-compute GPT-5.5 variant, publicly released in ChatGPT on April 23, 2026 alongside GPT-5.5 Thinking; OpenAI describes it as the same underlying model using a parallel test-time-compute setting. It is designed for harder questions and higher-accuracy work, is available in ChatGPT to Pro, Business, and Enterprise users, and became available through the API on April 24, 2026 as gpt-5.5-pro, with medium, high, and xhigh reasoning-effort settings.